Antimicrobial stewardship, procalcitonin testing, and rapid blood-culture identification to optimize sepsis care in critically ill adult patients: A quality improvement initiative.

We examined the effect of an antimicrobial stewardship program (ASP), procalcitonin testing and rapid blood-culture identification on hospital mortality in a prospective quality improvement project in critically ill septic adults. Secondarily, we have reported antimicrobial guideline concordance, acceptance of ASP interventions, and antimicrobial and health-resource utilization.

Synergism between chikungunya virus infection and rheumatoid arthritis on cytokine levels: Clinical implications?

Post-chikungunya virus (CHIKV) chronic arthritis shares several immunopathogenic mechanisms with rheumatoid arthritis (RA), which has led to discussions about the probable relationship between the two diseases. Indeed, some studies have suggested a role for CHIKV infection in RA development. However, to the best of our knowledge, the influence of CHIKV on previous RA has not yet been demonstrated. Herein, we analyzed the potential synergism between CHIKV infection and RA on cytokine and chemokine levels. For this, we compared the IL-1ß, IL-6, IL-10, IL-17A, CCL2, CXCL8, CXCL9 and CXCL10 levels, in addition to rheumatoid factor (RF) and C-reactive protein (CRP), in patients with post-CHIKV chronic arthritis (named CHIKV group), patients with RA (RA group), and patients with previous RA who were later infected by CHIKV (RA-CHIKV). History of CHIKV infection was confirmed by serology (IgG, ELISA). Cytokines/chemokines were quantified by flow cytometry. RF, CRP, age and sex data were obtained from medical records. IL-1ß, IL-6, IL-10 and IL-17A levels were significantly higher in RA-CHIKV compared to the other groups. CXCL8 levels were higher in the CHIKV group than in RA. CXCL9 was higher in CHIKV than in the RA-CHIKV group. CXCL10 was higher in CHIKV than in the other groups. FR levels were higher in RA than in the CHIKV group, and in RA-CHIKV than in CHIKV. No significant difference was observed in CCL2 and CRP, as well as in age and sex. Finally, our findings suggest an interplay between CHIKV infection and RA, which must be analyzed for its possible clinical impact.

Cost Analysis of a Transition Care Bundle Compared with Usual Care for COPD Patients Being Discharged from Hospital: Evaluation of a Randomized Controlled Trial.

BACKGROUND: Appropriate management of chronic obstructive pulmonary disease (COPD) patients following acute exacerbations can reduce the risk of future exacerbations, improve health status, and lower care costs. While a transition care bundle (TCB) was associated with lower readmissions to hospitals than usual care (UC), it remains unclear whether the TCB was associated with cost savings. OBJECTIVE: The aim of this study was to evaluate how this TCB was associated with future Emergency Department (ED)/outpatient visits, hospital readmissions, and costs in Alberta, Canada. METHODS: Patients who were aged 35 years or older, who were admitted to hospital for a COPD exacerbation, and had not been treated with a care bundle received either TCB or UC. Those who received the TCB were then randomized to either TCB alone or TCB enhanced with a care coordinator. Data collected were ED/outpatient visits, hospital admissions and associated resources used for index admissions, and 7-, 30- and 90-day post-index discharge. A decision model with a 90-day time horizon was developed to estimate the cost. A generalized linear regression was conducted to adjust for imbalance in patient characteristics and comorbidities, and a sensitivity analysis was conducted on the proportion of patients' combined ED/outpatient visits and inpatient admissions as well as the use of a care coordinator. RESULTS: Differences in length of stay (LOS) and costs between groups were statistically significant, although with some exceptions. Inpatient LOS and costs were 7.1 days (95% confidence interval [CI] 6.9-7.3) and Canadian dollars (CAN$) 13,131 (95% CI CAN$12,969-CAN$13,294) in UC, 6.1 days (95% CI 5.8-6.5) and CAN$7634 (95% CI CAN$7546-CAN$7722) in TCB with a coordinator, and 5.9 days (95% CI 5.6-6.2) and CAN$8080 (95% CI CAN$7975-CAN$8184) in TCB without a coordinator. Decision modelling indicated TCB was less costly than UC, with a mean (standard deviation [SD]) of CAN$10,172 (40) versus CAN$15,588 (85), and TCB with a coordinator was slightly less costly than without a coordinator (CAN$10,109 [49] versus CAN$10,244 [57]). CONCLUSION: This study suggests that the use of the TCB, with or without a care coordinator, appears to be an economically attractive intervention compared with UC.

Length of Stay and Home Discharge for Patients with Inpatient Stroke Rehabilitation.

OBJECTIVE: To examine temporal trends and geographic variations and predict inpatient rehabilitation (IPR) length of stay (LOS) and home discharge for stroke patients. METHODS: Patients aged ≥18 years who were admitted to an IPR facility in Alberta, Canada, between 04/2014 and 03/2018 (years 2014-2017) were included. Predictors of LOS and home discharge were examined using 2014-2016 data and validated using 2017 data. Multivariable linear regression (MLR), multivariable negative binomial (MNB), and multivariable quantile regressions (MQR) were used to examine LOS, and logistic regression was used for home discharge. RESULTS: We included 2686 rehabilitation admissions between 2014 and 2017. The mean LOS decreased (2014: 71 days; 2017: 62.1 days; p = 0.003) during the study period and was shortest in Edmonton (59.1 days) compared to Calgary (66 days) or other localities (70.8 days; p < 0.001). Three-quarters of patients were discharged home and this proportion remained unchanged between 2014 and 2017. Calgary patients were more likely to be discharged home than those in Edmonton (OR = 0.62; p = 0.019) or other localities (OR = 0.39; p = 0.011). The MLR and MNB models provided accurate prediction for the mean LOS (predicted = 59.9 and 60.8 days, respectively, vs. actual = 62.1 days; both p > 0.5), while the MQR model did so for the median LOS (predicted = 44.3 days vs. actual = 44 days; p = 0.09). The logistic regression resulted in 82.4% of correct prediction, a sensitivity of 91.6%, and a specificity of 50.7% for home discharge. CONCLUSIONS: Rehabilitation LOS decreased while the proportion of home discharge remained unchanged during the study period. Both varied across health zones. Identifiable statistical models provided accurate prediction with a separate patient cohort.

Optimal Planning of Health Services through Genetic Algorithm and Discrete Event Simulation: A Proposed Model and Its Application to Stroke Rehabilitation Care.

Background. Increasing demand for provision of care to stroke survivors creates challenges for health care planners. A key concern is the optimal alignment of health care resources between provision of acute care, rehabilitation, and among different segments of rehabilitation, including inpatient rehabilitation, early supported discharge (ESD), and outpatient rehabilitation (OPR). We propose a novel application of discrete event simulation (DES) combined with a genetic algorithm (GA) to identify the optimal configuration of rehabilitation that maximizes patient benefits subject to finite health care resources. Design. Our stroke rehabilitation optimal model (sROM) combines DES and GA to identify an optimal solution that minimizes wait time for each segment of rehabilitation by changing care capacity across different segments. sROM is initiated by generating parameters for DES. GA is used to evaluate wait time from DES. If wait time meets specified stopping criteria, the search process stops at a point at which optimal capacity is reached. If not, capacity estimates are updated, and an additional iteration of the DES is run. To parameterize the model, we standardized real-world data from medical records by fitting them into probability distributions. A meta-analysis was conducted to determine the likelihood of stroke survivors flowing across rehabilitation segments. Results. We predict that rehabilitation planners in Alberta, Canada, have the potential to improve services by increasing capacity from 75 to 113 patients per day for ESD and from 101 to 143 patients per day for OPR. Compared with the status quo, optimal capacity would provide ESD to 138 (s = 29.5) more survivors and OPR to 262 (s = 45.5) more annually while having an estimated net annual cost savings of $25.45 (s = 15.02) million. Conclusions. The combination of DES and GA can be used to estimate optimal service capacity. Highlights: We created a hybrid model combining a genetic algorithm and discrete event simulation to search for the optimal configuration of health care service capacity that maximizes patient outcomes subject to finite health system resources.We applied a probability distribution fitting process to standardize real-world data to probability distributions. The process consists of choosing the distribution type and estimating the parameters of that distribution that best reflects the data. Standardizing real-word data to a best-fitted distribution can increase model generalizability.In an illustrative study of stroke rehabilitation care, resource allocation to stroke rehabilitation services under an optimal configuration allows provision of care to more stroke survivors who need services while reducing wait time.Resources needed to expand rehabilitation services could be reallocated from the savings due to reduced wait time in acute care units. In general, the predicted optimal configuration of stroke rehabilitation services is associated with a net cost savings to the health care system.

Ultra-low dose CT abdomen and pelvis for the detection of acute abdominal pathology in the emergency room: initial experience from an academic hospital.

PURPOSE: The aim of this study is to describe our initial experience using ULDCT performed in the emergency room in the evaluation of acute abdominal pathology. METHODS: Data from consecutive patients who underwent ULDCT for assessment of bowel obstruction, free intraperitoneal air, unexplained abdominal pain, or fecal loading for constipation between June 1, 2016 and March 31, 2017 was retrospectively assessed. Demographic data, radiation dose, CT findings, and clinical outcomes including performance of full dose contrast-enhanced CT (CECT), hospitalization, and surgery was collected. Concordance of ULDCT to CECT was calculated. RESULTS: ULDCT was performed in 325 patients (188 women and 137 men; mean age, 65.1 years). ULDCT detected acute abdominal pathology in 134/325 (41.2%), and in 89/134 (66.4%) it was concordant with the clinical working diagnosis. The average dose length product (DLP) was 101.6 mGy cm (range 51.7-614; median, 82.6). CECT was performed in 44/325 patients (13.5%). In 7/44 (15.9%), CECT identified discordant findings which likely impacted management. A greater proportion of patients were admitted to hospital after a positive ULDCT 99/137 (72.3%), compared to those with a negative study 81/188 (43.1%); p < 0.0001(Chi2, 27.30). Of those admitted to hospital, 11/99 (11.1%) with positive ULDCT had surgery compared to 1/81 (1.2%) with a negative ULDCT; p < 0.008 (Chi2, 6.98). CONCLUSION: With its high clinical yield and similar radiation dose, ULDCT appears as a suitable alternative to abdominal radiography for the detection of select acute abdominal pathology in the emergency room.

Open-source software for ultrasound-based guidance in spinal fusion surgery.

Spinal instrumentation and surgical manipulations may cause loss of navigation accuracy requiring an efficient re-alignment of the patient anatomy with pre-operative images during surgery. While intra-operative ultrasound (iUS) guidance has shown clear potential to reduce surgery time, compared with clinical computed tomography (CT) guidance, rapid registration aiming to correct for patient misalignment has not been addressed. In this article, we present an open-source platform for pedicle screw navigation using iUS imaging. The alignment method is based on rigid registration of CT to iUS vertebral images and has been designed for fast and fully automatic patient re-alignment in the operating room. Two steps are involved: first, we use the iUS probe's trajectory to achieve an initial coarse registration; then, the registration transform is refined by simultaneously optimizing gradient orientation alignment and mean of iUS intensities passing through the CT-defined posterior surface of the vertebra. We evaluated our approach on a lumbosacral section of a porcine cadaver with seven vertebral levels. We achieved a median target registration error of 1.47 mm (100% success rate, defined by a target registration error <2 mm) when applying the probe's trajectory initial alignment. The approach exhibited high robustness to partial visibility of the vertebra with success rates of 89.86% and 88.57% when missing either the left or right part of the vertebra and robustness to initial misalignments with a success rate of 83.14% for random starts within ±20° rotation and ±20 mm translation. Our graphics processing unit implementation achieves an efficient registration time under 8 s, which makes the approach suitable for clinical application.

Cost-effectiveness analysis of a randomized study of depression treatment options in primary care suggests stepped-care treatment may have economic benefits.

BACKGROUND: The stepped-care pathway (SCP) model has previously been found to be clinically effective for depressive disorder in some studies, but not all. Several groups have suggested that a stepped-care approach is the most appropriate in primary care. There is relatively little information, however, regarding which specific stepped-care pathway may be best. This analysis aimed to determine cost-effectiveness of a stepped-care pathway for depression in adults in primary care versus standard care (SC), treatment-as-usual (TAU), and online cognitive behavioural therapy (CBT). METHODS: We conducted a randomized trial with 1400 participants and 12-week follow-up to assess the impact of the four treatment options on health-related quality of life and depression severity. Costs for the groups were calculated on the basis of physician, outpatient, and inpatient services using administrative data. We then calculated the incremental cost-effectiveness ratios using this information. Cost-effectiveness acceptability curves and incremental cost-effectiveness scatterplots were created using Monte Carlo simulation with 10,000 replications. A subgroup analysis was conducted for participants who screened as depressed at baseline. RESULTS: For all participants, TAU was the most expensive followed by CBT, SC, and SCP. QALYs were highest in SCP, followed by SC, CBT, and TAU. In the depressed subgroup, TAU was still the most expensive, followed by SC, SCP, and CBT, while QALYs were still highest in SCP, followed by SC, CBT, and TAU. The cost-effectiveness acceptability curves suggested that SCP had a higher probability for cost-effectiveness than the other three alternatives in all participants. In the depressed subgroup, CBT was associated with the highest probability of cost-effectiveness for a willingness-to-pay cut-off of less than approximately $50,000, while SCP was the highest at a cut-off higher than $50,000. There is considerable uncertainty around the cost-effectiveness estimates. CONCLUSIONS: Our analysis showed that even where there are no clinically significant differences in health outcomes between treatment approaches, there may be economic benefit from implementing the stepped-care model. While more work is required to identify the most clinically effective versions of a stepped-care pathway, our findings suggest that the care pathway may have potential to improve health care system value. TRIAL REGISTRATION: NCT01975207 . The trial was prospectively registered on 4 November 2013.

Toward real-time rigid registration of intra-operative ultrasound with preoperative CT images for lumbar spinal fusion surgery.

PURPOSE: Accurate and effective registration of the vertebrae is crucial for spine surgical navigation procedures. Patient movement, surgical instrumentation or inadvertent contact with the tracked reference during the intervention may invalidate the registration, requiring a rapid correction of the misalignment. In this paper, we present a framework to rigidly align preoperative computed tomography (CT) with the intra-operative ultrasound (iUS) images of a single vertebra. METHODS: We use a single caudo-cranial axial sweep procedure to acquire iUS images, from which the scan trajectory is exploited to initialize the registration transform. To refine the transform, locations of the posterior vertebra surface are first extracted, then used to compute the CT-to-iUS image intensity gradient-based alignment. The approach was validated on a lumbosacral section of a porcine cadaver. RESULTS: We achieved an overall median accuracy of 1.48 mm (success rate of 84.42%) in [Formula: see text] 11 s of computation time, satisfying the clinically accepted accuracy threshold of 2 mm. CONCLUSION: Our approach using intra-operative ultrasound to register patient vertebral anatomy to preoperative images matches the clinical needs in terms of accuracy and computation time, facilitating its integration into the surgical workflow.

Health Technology Optimization Analysis: Conceptual Approach and Illustrative Application.

We present a conceptual approach to determine the optimal solution to delivering a health technology, consistent with the objective of maximizing patient outcomes subject to resources available to a publicly funded health system. The article addresses two key policy questions: 1) adding system values through appropriate planning of health services delivery and 2) considering the tradeoff between patient outcomes and costs to the health system through appropriate use of health technologies for conditions with time-dependent treatment outcomes. We develop a health technology optimization framework that considers geographical variation and searches for the best delivery method through a pairwise comparison of all possible strategies, factoring in controlled variables including disease epidemiology, time or distance to hospitals, available medical services, treatment eligibility, treatment efficacy, and costs. Taking variations of these factors into account would help support a more efficient allocation of health resources. Drawing identified strategies together then creates a map of optimal strategies. We apply the proposed method to a policy-relevant health technology assessment of endovascular therapy (EVT) for treating acute ischemic stroke. The best strategy for providing EVT relies on the geographical location of stroke onset and the decision maker's preference for either patient outcomes or economic efficiency. The proposed method produced an optimization map showing the optimal strategy for EVT delivery, which maximizes patient outcomes while minimizing health system costs. In the illustrative case study, there were no tradeoffs between health outcomes and costs, meaning that the delivery strategies that were clinically optimal for patients were also the most cost-effective. In conclusion, the health technology optimization approach is a useful tool for informing implementation decisions and coordinating the delivery of complex health services such as EVT.

User-friendly freehand ultrasound calibration using Lego bricks and automatic registration.

PURPOSE: As an inexpensive, noninvasive, and portable clinical imaging modality, ultrasound (US) has been widely employed in many interventional procedures for monitoring potential tissue deformation, surgical tool placement, and locating surgical targets. The application requires the spatial mapping between 2D US images and 3D coordinates of the patient. Although positions of the devices (i.e., ultrasound transducer) and the patient can be easily recorded by a motion tracking system, the spatial relationship between the US image and the tracker attached to the US transducer needs to be estimated through an US calibration procedure. Previously, various calibration techniques have been proposed, where a spatial transformation is computed to match the coordinates of corresponding features in a physical phantom and those seen in the US scans. However, most of these methods are difficult to use for novel users. METHODS: We proposed an ultrasound calibration method by constructing a phantom from simple Lego bricks and applying an automated multi-slice 2D-3D registration scheme without volumetric reconstruction. The method was validated for its calibration accuracy and reproducibility. RESULTS: Our method yields a calibration accuracy of [Formula: see text] mm and a calibration reproducibility of 1.29 mm. CONCLUSION: We have proposed a robust, inexpensive, and easy-to-use ultrasound calibration method.

Postpartum sacral insufficiency fractures.

Postpartum sacral insufficiency fracture is an uncommon occurrence that is often under-diagnosed because its symptoms of low back, buttock and groin pains may initially be attributed to physiologic biomechanical changes caused by pregnancy or to intervertebral disc disease. We present a case of bilateral sacral insufficiency fractures in a 37-year-old postpartum woman with osteopenic bone mineral density confirmed by dual energy X-ray absorptiometry. The symptoms were initially suspected to be of discogenic cause, and the fractures were incidentally appreciated at the edge of a lumbar spine magnetic resonance image. Therefore, it is important to keep in mind this potential diagnosis when examining imaging studies of postpartum patients. For women who present other risk factors of osteoporosis, imaging of the entire sacrum should be part of the imaging studies. If sacral stress fractures are diagnosed, further evaluation for bone mineral density and underlying metabolic bone disease is recommended.

[Computerized system validation of clinical researches].

Validation is a documented process that provides a high degree of assurance. The computer system does exactly and consistently what it is designed to do in a controlled manner throughout the life. The validation process begins with the system proposal/requirements definition, and continues application and maintenance until system retirement and retention of the e-records based on regulatory rules. The objective to do so is to clearly specify that each application of information technology fulfills its purpose. The computer system validation (CSV) is essential in clinical studies according to the GCP standard, meeting product's pre-determined attributes of the specifications, quality, safety and traceability. This paper describes how to perform the validation process and determine relevant stakeholders within an organization in the light of validation SOPs. Although a specific accountability in the implementation of the validation process might be outsourced, the ultimate responsibility of the CSV remains on the shoulder of the business process owner-sponsor. In order to show that the compliance of the system validation has been properly attained, it is essential to set up comprehensive validation procedures and maintain adequate documentations as well as training records. Quality of the system validation should be controlled using both QC and QA means.

[Integrated e-clinical solutions in clinical research].

Implementation of information technology in clinical research has resulted in revolutionary changes in drug development. Based on the good clinical practice (GCP) requirements on data, processes and documentations, and the era of fast growth in clinical studies using up-to-date information technology, we explore an integrated e-clinical solution in clinical studies in China.

Ultrasound-CT registration of vertebrae without reconstruction.

PURPOSE: While robust and accurate, our previously developed volume-to-volume ultrasound-CT registration of vertebrae required that the 2D ultrasound slices be reconstructed into a 3D volume, a time-consuming step that increased the total registration time per vertebra. We have modified our registration technique to a slices-to-volume strategy to eliminate the ultrasound reconstruction step in order to make the total registration time more practical intraoperatively. METHODS: The slices-to-volume registration is achieved by performing backward scan line tracing on individual ultrasound slices as they are acquired, and then registering them as a group to the posterior vertebral surface extracted from the pre-operative CT image. The technique is validated using a lumbosacral Sawbones phantom and the lumbosacral section of three porcine cadavers. RESULTS: The slices-to-volume registration reduced the total registration time per vertebra from 8 to 4 min. The registration accuracy and robustness of the slices-to-volume registration were found to be equal or superior to those of our previous volume-to-volume registration. In addition, a trade-off was found between registration accuracy and registration speed by changing the number of ultrasound slices used in the registration. CONCLUSIONS: The slices-to-volume ultrasound-CT registration significantly reduces the total registration time per vertebra, making this automated technique more practical intraoperatively.

Validation of a hybrid Doppler ultrasound vessel-based registration algorithm for neurosurgery.

PURPOSE: We describe and validate a novel hybrid nonlinear vessel registration algorithm for intra-operative updating of preoperative magnetic resonance (MR) images using Doppler ultrasound (US) images acquired on the dura for the correction of brain-shift and registration inaccuracies. We also introduce an US vessel appearance simulator that generates vessel images similar in appearance to that acquired with US from MR angiography data. METHODS: Our registration uses the minimum amount of preprocessing to extract vessels from the raw volumetric images. This prevents the removal of important registration information and minimizes the introduction of artifacts that may affect robustness, while reducing the amount of extraneous information in the image to be processed, thus improving the convergence speed of the algorithm. We then completed 3 rounds of validation for our vessel registration method for robustness and accuracy using (i) a large number of synthetic trials generated with our US vessel simulator, (ii) US images acquired from a real physical phantom made from polyvinyl alcohol cryogel, and (iii) real clinical data gathered intra-operatively from 3 patients. RESULTS: Resulting target registration errors (TRE) of less than 2.5 mm are achieved in more than 90 % of the synthetic trials when the initial TREs are less than 20 mm. TREs of less than 2 mm were achieved when the technique was applied to the physical phantom, and TREs of less than 3 mm were achieved on clinical data. CONCLUSIONS: These test trials show that the proposed algorithm is not only accurate but also highly robust to noise and missing vessel segments when working with US images acquired in a wide range of real-world conditions.

Validation of automated ultrasound-CT registration of vertebrae.

PURPOSE: Image-guided spine surgery requires registration of the patient anatomy and preoperative computed tomography (CT) images. A technique for intraoperative ultrasound image registration to preoperative CT scans was developed and tested. Validation of the ultrasound-CT registration technique was performed using porcine cadavers. METHODS: An ultrasound-CT registration technique was evaluated using 18 thoracic and lumbar vertebrae of 3 porcine cadavers with 10 different sweep patterns for ultrasound acquisition. For each sweep pattern at each vertebra, 100 randomly simulated initial misalignments were introduced. Each misalignment was registered. The resulting registration transformations were compared to gold standard registrations based on implanted fiducials to assess accuracy and robustness of the technique. RESULTS: The orthogonal-sweep acquisition was found to perform best and yielded a registration accuracy of 1.65 mm across all vertebrae on all porcine cadavers, where 82.5% of the registrations resulted in target registration errors below the 2 mm threshold recommended by a joint report from the experts in the field. In addition, we found that registration accuracy varies by the sweep pattern and vertebral level, but neighboring vertebrae tend to result in statistically similar accuracy. Ultrasound-CT registration took an average of 2.5 min to run, and the total registration time per vertebra (also including time for ultrasound acquisition and reconstruction) is approximately 8 min. CONCLUSIONS: A previously described ultrasound-CT registration technique yields clinically acceptable accuracy and robustness on multiple vertebrae across multiple porcine cadavers. The total registration time is shorter than that of surface point-based manual registration.

New prototype neuronavigation system based on preoperative imaging and intraoperative freehand ultrasound: system description and validation.

PURPOSE: The aim of this report is to present IBIS (Interactive Brain Imaging System) NeuroNav, a new prototype neuronavigation system that has been developed in our research laboratory over the past decade that uses tracked intraoperative ultrasound to address surgical navigation issues related to brain shift. The unique feature of the system is its ability, when needed, to improve the initial patient-to-preoperative image alignment based on the intraoperative ultrasound data. Parts of IBIS Neuronav source code are now publicly available on-line. METHODS: Four aspects of the system are characterized in this paper: the ultrasound probe calibration, the temporal calibration, the patient-to-image registration and the MRI-ultrasound registration. In order to characterize its real clinical precision and accuracy, the system was tested in a series of adult brain tumor cases. RESULTS: Three metrics were computed to evaluate the precision and accuracy of the ultrasound calibration. 1) Reproducibility: 1.77 mm and 1.65 mm for the bottom corners of the ultrasound image, 2) point reconstruction precision 0.62-0.90 mm: and 3) point reconstruction accuracy: 0.49-0.74 mm. The temporal calibration error was estimated to be 0.82 ms. The mean fiducial registration error (FRE) of the homologous-point-based patient-to-MRI registration for our clinical data is 4.9 ± 1.1 mm. After the skin landmark-based registration, the mean misalignment between the ultrasound and MR images in the tumor region is 6.1 ± 3.4 mm. CONCLUSIONS: The components and functionality of a new prototype system are described and its precision and accuracy evaluated. It was found to have an accuracy similar to other comparable systems in the literature.

Towards accurate, robust and practical ultrasound-CT registration of vertebrae for image-guided spine surgery.

PURPOSE: Accurate registration of patient anatomy and preoperative computed tomography (CT) images is key to successful image-guided spine surgery. Current manual landmark and surface-based techniques are time-consuming and not always accurate. Intraoperative ultrasound imaging of the vertebrae, combined with automated registration, could improve surgery by improving accuracy, reducing operative time, and decreasing invasiveness. METHODS: We present a simple ultrasound-CT registration technique that is automated, accurate, and robust. Registration is achieved by aligning the posterior vertebral surface, extracted from both CT and ultrasound images, using a forward and a backward scan line tracing method, respectively. The registration technique is validated using a simple plastic phantom in a water bath and a more realistic porcine cadaver in a simulation of open back surgery. RESULTS: Clinically relevant accuracy was estimated by comparing automated registrations with gold standard imaging fiducial-based reference transformations, which yielded target registration errors of under 1 mm for the plastic phantom and under 1.6 mm for the porcine cadaver. CONCLUSIONS: Our registration technique demonstrates good accuracy and robustness under clinically realistic conditions and thus warrants further studies on its surgical application.

Dietary n-3:n-6 fatty acid ratios differentially influence hormonal signature in a rodent model of metabolic syndrome relative to healthy controls.

Dietary ratios of omega-3 (n-3) to omega-6 (n-6) polyunsaturated fatty acids (PUFAs) have been implicated in controlling markers of the metabolic syndrome, including insulin sensitivity, inflammation, lipid profiles and adiposity. However, the role of dietary PUFAs in regulating energy systems in healthy relative to metabolic diseased backgrounds has not been systematically addressed. We used dietary manipulation of n-3 to n-6 PUFA ratios in an animal model of metabolic syndrome and a related healthy line to assay feeding behavior and endocrine markers of feeding drive and energy regulation. Two related lines of rodents with a healthy and a metabolic syndrome phenotype were fed one of two isocaloric diets, comprised of either a 1:1 or a 1:30 n-3 to n-6 ratio, for 30 days. Food intake and weight gain were monitored; and leptin, ghrelin, adiponectin and a suite of hypothalamic neuropeptides involved in energy regulation were assayed following the dietary manipulation period. There was no difference in caloric intake or weight gain between diet groups, however there was a significant interaction between diet and phenotypic line on central and peripheral markers of energy homeostasis. Thus serum levels of leptin, acylated-ghrelin and adiponectin, and mRNA levels of the anorexigenic hypothalamic neuropeptide, cocaine-amphetamine related transcript (CART), showed differential, dietary responses with HCR rats showing an increase in anorexigenic signals in response to unbalanced n-3:6 ratios, while LCR did not. These data are the first to demonstrate that a rodent line with a metabolic syndrome-like phenotype responds differentially to dietary manipulation of n-3 and n-6 fatty acids relative to a related healthy line with regard to endocrine markers of energy homeostasis. The dietary n-3:n-6 ratios used in this experiment represent extreme points of natural human diets, however the data suggest that optimal recommendations regarding omega-3 and omega-6 intake may have differing effects in healthy subjects relative to metabolic syndrome patients. Further research is necessary to establish these responses in human populations.